linux-kernel - [34-longterm 229/260] x86, olpc: Don't retry EC commands forever

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Date:	Sun,  2 Jan 2011 02:18:45 -0500
From:	Paul Gortmaker <paul.gortmaker@...driver.com>
To:	stable@...nel.org, linux-kernel@...r.kernel.org
Cc:	stable-review@...nel.org, Paul Fox <pgf@...top.org>,
	Daniel Drake <dsd@...top.org>, dilinger@...ued.net,
	Ingo Molnar <mingo@...e.hu>,
	Paul Gortmaker <paul.gortmaker@...driver.com>
Subject: [34-longterm 229/260] x86, olpc: Don't retry EC commands forever

From: Paul Fox <pgf@...top.org>

commit 286e5b97eb22baab9d9a41ca76c6b933a484252c upstream.

Avoids a potential infinite loop.

It was observed once, during an EC hacking/debugging
session - not in regular operation.

Signed-off-by: Daniel Drake <dsd@...top.org>
Cc: dilinger@...ued.net
Signed-off-by: Ingo Molnar <mingo@...e.hu>
Signed-off-by: Paul Gortmaker <paul.gortmaker@...driver.com>
---
 arch/x86/kernel/olpc.c |    5 ++++-
 1 files changed, 4 insertions(+), 1 deletions(-)

diff --git a/arch/x86/kernel/olpc.c b/arch/x86/kernel/olpc.c
index 8297160..a23b382 100644
--- a/arch/x86/kernel/olpc.c
+++ b/arch/x86/kernel/olpc.c
@@ -117,6 +117,7 @@ int olpc_ec_cmd(unsigned char cmd, unsigned char *inbuf, size_t inlen,
 	unsigned long flags;
 	int ret = -EIO;
 	int i;
+	int restarts = 0;
 
 	spin_lock_irqsave(&ec_lock, flags);
 
@@ -173,7 +174,9 @@ restart:
 			if (wait_on_obf(0x6c, 1)) {
 				printk(KERN_ERR "olpc-ec:  timeout waiting for"
 						" EC to provide data!\n");
-				goto restart;
+				if (restarts++ < 10)
+					goto restart;
+				goto err;
 			}
 			outbuf[i] = inb(0x68);
 			printk(KERN_DEBUG "olpc-ec:  received 0x%x\n",
-- 
1.7.3.3

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